Wireless aerial for use on short waves



Fe. 18, 1936. N. WELLS ET AL v L L WIRELESS AERIAL FOR USE ON SHORT WAVES Filed April 4, 1955 32 -82 -82 Z a M M M \m H w w v iuq wire '1 7 \/?7 2 INVENTOR NORMA/V WELLS ERNEST GEE/V BY AT'TORNEY Patented Feb. 18, 1936 UNITED STATES 2,3i,lt

PATENT QFEIE WIRELESS AERIAL FOR USE ON SHORT WAVES Application April 4, 1933, Serial No. 664,374 In Great Britain April 13, 1932 Claims.

This invention relates to wireless aerials for use on short waves and has for its object to provide an improved short wave aerial which is long as compared to the half wave length unit of 5 length and which shall be capable of giving sharply directional characteristics when embodied in an aerial system in conjunction with other similar aerials. More particularly the invention relates to short wave aerials of the kind wherein so-called phasing units are inserted so as to cause the effective, 1. e. the radiating, high frequency current to be of the same sign at any instant throughout the length of the aerial. A well known aerial arrangement of this kind is described for example in British Patent No. 242,342 which discloses aerial systems consisting of aerials long in comparison with the half wave length and wherein phasing coils or other devices are inserted at alternate half wave lengths so as to suppress radiation from those alternate half wave lengths and thereby to cause the effective or radiating high frequency current to be of the same sign at any instant throughout the aerial.

Numerous proposals for inserting'phasing devices in aerials for use on short waves have been made, but so far as the present applicants are aware all such proposals have the disadvantages I of lack of symmetry and/or liability to set up refiection. For example, in the known. proposals wherein the phasing units consist of half wave lengths of the aerial bent back upon themselves so as to be non-radiating, there is lack of symmetry, while in those proposals embodying phasing units in the form of lumped inductances or coils, the coils give rise to reflection and consequently in part neutralize the beneficial efiect which is obtained by making the aerial long as compared to the half wave length and inserting the phasing units. Lack of symmetry, of course, results in a distortion of the electromagnetic field surrounding the aerial thereby deflecting the main axis of propagation.

The principal object of the present invention is to avoid these disadvantages.

According to this invention the phasing unit or units in an aerial of the kind referred to is v or are constituted by a closed Lecher wire frame or its equivalent, said frame being symmetrical with respect to the main direction or length of the aerial. a The invention is illustrated schematically in the accompanying drawing, Figures 1 and 2 of which illustrate two embodiments.

Referring to Figure 1 which shows one way of carrying out the invention, a short wave aerial consists of three portions, two being radiating and the third substantially non-radiating. Starting from the bottom of the aerial, the three per" tions consist first of a vertical straight portion R1 substantially a half wave length long, second of a substantially non-radiating portion NR also substantially a half wave length in electrical length, and third a second radiating portion R2 substantially a half wave length long, the portions R1 and R2 being as shown in the same straight line. The non-radiating portion NR con.- sists of a Lecher wire frame which constitutes the phasing unit, this frame consisting of a pair of Lecher wires which join the adjacent ends of the portions R1 and R2 together, one Lecher wire extending out, say to the right of the aerial in a rectangular half loop and the other extending out to the left in a complementary and symmetri cal rectangular half loop. Thus the phasing unit consists, as it were, of a rectangular frame whose longer sides are at right angles to the radiating portion of the aerial and whose shorter sides are parallel thereto, said radiating portions being joined each to the middle point of one of the two longer sides of the rectangle. The invention is of considerable advantage when applied to so -called beam aerial systems in which application it presents the important advantage of substantially simplifying and cheapening the feeding and constructional arrangements. In one such application illustrated in Figure 2 a beam aerial system consists of a plurality of aerials l, 2, 3, 4 each of which, as above described, comprises two radiating portions R1 R2 joined together by a non-radiating Lecher wire frame NR, these aerials being mounted in a plane so as toform a sheet aerial system of the well-known general beam aerial type. The aerials are arranged side by side as stated and the adjacent vertical sides of the rectangular Lecher wire frames NR on two adjacent aerials are preferably combined into a single wire as illustrated, so that the horizontal portions of the rectangular Lecher wire frames are in two parallel horizontal lines, there being a vertical portion joining these lines midway between each pair of adjacent aerials, these horizontal lines being also joined together by vertical portions at the ends of the horizontal lines and outside the extreme aerials. The actual spacing of the various wires in the beam aerial system just described will, of course, depend upon design requirements, but in practice the vertical height of the rectangular Lecher wire frames will be chosen at a value such as will give approximately the optimum actual coupling between the adjacent closed Lecher wire circuits. If this vertical height be d and if D be the spacing between the radiating portions of adjacent aerials a practical example of dimensioning is D=0.45 and (1:.045 A. In Figure 2 the arrow heads indicate the directions of the current in the various parts of the aerial system. A beam aerial system as just described may very satisfactorily and simply be energized by a single two-wire feeder. Each of the wires of the feeder may be connected by tails to two points on either side of the middle point of one of the two horizontal lines in which the longer sides of the rectangular Lecher frames lie, the other wires being similarly connected by tails to two similar points in the other horizontal line.

It is, of course, to be understood that the invention is not limited to aerials which are only approximately one .active wave length long; for example, the beam aerial arrangement just described may be made of greater overall height, each aerial may be approximately two active wave lengths long. In this case each aerial will consist of four radiating portions in the same straight line, there being three rectangular Lecher wire frames one between each pair of radiating portions. The adjacent Lecher wire frames are coupled or joined together in a similar manner for each horizontal row thereof, there being thus six horizontal wires running right across the aerial system (each pair of horizontal wires corresponding to the longer sides of a row of rectangular Lecher frames) while feeding to the whole aerial system may be effected by a single two-wire feeder connected as above described symmetrically with respect to the whole aerial system, i. e. the wires of the feeder are connected to the two horizontal wires proper of the middle set of rectangular Lecher frames. Again it is not necessary that the radiating portions of an aerial or aerial system in accordance with this invention be in a vertical straight line since they may be in a horizontal straight line or at any other inclination as design requirements may dictate.

It will be appreciated that aerial systems in accordance with this invention are simple and cheap to construct and give substantially perfect symmetry. Furthermore, the standing wave of current in any one of the Lecher wire frames will be of the same general form as that in the radiating portions of the aerial and will, therefore, not (as. in the case of a phasing unit constitutect by an inserted coil) give rise to a sharply rising and falling wave of standing current. "As a result, reflection, which is, of course, a consequence of sharp changes in the wave of standing current, will be substantially completely avoided.

It-is, of course, to be understood that each of the two Lecher wires which together constitute a Lecher wire frame as employed in carrying out this invention, is, in the examples above described, substantially one-half wave length long, the total effective length of the frame being onehalf wave length since the two wires are in parallel. Further, although for the sake of con.- venience in description separate wires have been referred to as constituting different parts of the aerial, it is, of course, not necessary that physically separate wires should be employed, and, in practice, wires which are in the same straight line and end to end would be: constituted by a single wire.

We claim:

1. A short wave aerial system comprising two approximately half wave length linear radiating elements extending on the same straight line and separated by a phasing unit, the latter consisting of a substantially non-radiating full wave length wire bent back upon itself to constitute a substantially rectangular wire frame having opposite ends symmetrically connected to said radiating elements.

2. A short wave aerial system comprising two substantially half wave length linear radiating elements extending on the same straight line and separated by a phasing unit, the latter consisting of two substantially non-radiating half wave length wires bent back upon themselves to constitute substantially rectangular wire frame, the longer sides of said wire frame being perpendicular to said radiating elements, and the shorter sides being parallel to said elements.

3. An aerial system comprising two linear radiating elements extending on the same straight line and separated by a non-radiating phasing unit, the latter consisting of a wire frame of rectangular form having an overall length of approximately one wave length, said frame comprising two parallel horizontal portions joined together by vertical portions at the ends of said horizontal portions, each of said linear radiating elements being connected to a horizontal portion at substantially the center of said horizontal portion.

4. An aerial system comprising two linear radiating elements extending on the same straight line and separated by a non-radiating phasing unit, the latter consisting of a closed Lecher wire frame, said frame comprising two parallel portions joined together by shorter portions at the ends of said longer portions, the total electrical length of said parallel portions and said shorter portions of said frame being a multiple of a wave length, each of said linear radiating elements being connected to one of said longer portions at substantially the center of said longer portion whereby the wire frame extends outwardly on opposite sides of the radiating elements.

5. An aerial system comprising two linear radiating elements extending on the same straight line and separated by a non-radiating phasing unit, the latter consisting of a wire frame, said frame comprising two U shaped loops each approximately one half wave length long, said loops being complementary so as to make a substantially symmetrically closed loop, each of said linear radiating elements being connected to one of the junction points of said two U shaped loops whereby the wire frame extends outwardly on opposite sides of the radiating elements.

6. An aerial system comprising two linear radiating elements extending on the same straight line and separated by a non-radiating phasing unit, the latter consisting of a wire frame of substantially rectangular form having an overall length of approximately an odd multiple of one wave length, said frame comprising two parallel wires joined together by shorter wires at the ends of said parallel wires, each of said linear radiating elements being connected to one of said longer wires at substantially the center of said longer wire whereby the wire frame extends outwardly on opposite sides of the radiating elements, and another similar radiating arrangement having radiating elements in the same plane with and parallel to said first radiating elements, the nonradiating phasing units of both arrangements 75 being adjacent each other and so arranged that the parallel longer wires of both frames make two substantially straight lines.

'7. An aerial system in accordance with claim 6 characterized in this, that the distance between the parallel radiating elements is equal to 0.45 wave lengths and the spacing between the parallel longer wires of the frames is 0.045 wave lengths.

8. A system in accordance with claim 6 characterized in this, that the adjacent shorter wires of the rectangular frames are combined into a single wire.

9. A short wave aerial system comprising two substantially half wave length linear radiating elements extending on the same straight line and separated by a non-radiating phasing unit, the latter consisting of a Lecher wire frame of substantially rectangular form having an effective length approximately equal to half the length of the communication wave, said frame comprising two parallel, closely spaced horizontal wires joined together by shorter wires at the ends of said horizontal wires, each of said linear radiating elements being connected to a horizontal wire at substantially the center of said horizontal wire.

10. An aerial system comprising two linear radiating elements extending on the same straight line and separated by a non-radiating phasing unit, the latter consisting of a wire frame of substantially rectangular form having an overall length of approximately an odd multiple of one wave length, said frame comprising two parallel portions joined together by shorter portions at the ends of said longer portions, each of said linear radiating elements being connected to one of said longer portions at substantially the center of said longer portion whereby the wire frame extends outwardly on opposite sides of the radiating elements, and another similar radiating arrangement having radiating elements in the same plane with and parallel to said first radiating elements, the non-radiating phasing units of both arrangements being adjacent each other and so arranged that the parallel longer portions of both frames make two substantially straight lines, the adjacent shorter portions being combined into a single wire, a two wire transmission line and connections from each wire of said line to two points on one of said straight lines, both points being on difierent sides of said shorter portion.

NORMAN WELLS.. ERNEST GREEN. 

